1. Technical Field
The present invention relates to a side gas injector installed in a plasma reaction chamber. More particularly, the present invention relates to a side gas injector for a plasma reaction chamber, for radially uniformly jetting a reaction gas in the lateral direction of a wafer, thereby uniformly diffusing the reaction gas to an edge part of the wafer and, through an independent mass flow control, improving an etching uniformity in the edge part of the wafer.
2. Description of the Related Art
Generally, a large size wafer used for a semiconductor integrated circuit device, a glass substrate being a key part used for a Liquid Crystal Display (LCD), etc. form an ultra-fine circuit or pattern on a surface in a desired form by forming several thin film layers on the surface and selectively removing only part of the thin film layers.
Fine circuit or pattern manufacturing is commonly carried out through many manufacturing processes such as a rinse process, a deposition process, a photolithography process, a plating process, an etching process, etc.
The above various treatment processes are carried out after the wafer or substrate is inputted to a chamber or reaction furnace capable of isolating the wafer or substrate from the external.
Among the above processes, particularly, the etching process is a process of removing desired materials from a wafer surface through a physical or chemical reaction of a plasma state by jetting a suitable reaction gas (e.g., carbon tetrafluoride (CF4), chlorine gas (Cl2), hydrogen bromide (HBr), oxygen (O2), argon (Ar), etc.) into the chamber or reaction furnace. The etching process is a process of selectively removing a portion not covered with a photoresist using a photoresist pattern as a mask and forming a fine circuit on a surface.
In the etching process, it is of significance best of all to maintain an etching uniformity in the whole wafer surface. Therefore, by uniformly diffusing a reaction gas into the reaction chamber, the etching process secures plasma uniformity within the reaction chamber and improves the etching uniformity, thus realizing the prevention of a process error.
For the sake of the uniform diffusion of the reaction gas within the reaction chamber, the conventional art sought to secure an etching uniformity in a center part and edge part of a wafer by installing a jet nozzle at a top of the reaction chamber and making different a mass flow of gas jetted to each of an upper center and edge of the reaction chamber.
However, the above-described conventional gas injector has the following problems.
First, as a wafer is large scaled, a pattern density difference between the center part and edge part of the wafer increases. Thus, a difference of a consumption amount of a reaction gas causes the local exhaust of an etching source, so leading to the occurrence of a phenomenon in which a difference of an etching speed between the center part and edge part of the wafer.
Second, there is a problem in which a by-product caused by fluoromethane (CHF3), methylene fluoride (CH2F2), etc. used for an increase of selectivity is decomposed in the wafer edge and performs a passivation action of suppressing etching, thus greatly reducing an etch rate of the edge part or decreasing an etching width (i.e., a Critical Dimension (CD)).
Third, in case that a reaction gas is jet with its different mass flow in the direction from the top of the reaction chamber to the wafer edge, a degree of diffusion of the reaction gas varies depending on process condition while the reaction gas reaches the edge part of the wafer. This leads to making it difficult to independently control a distribution of the reaction gas in the edge part of the wafer, thus not being able to secure an etching uniformity in the edge part of the wafer.